Method for inhibiting bacterial activity in petroleum



United States Patent Ofihce 3,035,887 Patented May 22, 1962 3,035,887 METHOD FOR INHIBITING BACTERIAL ACTIVITY IN PETROLEUM George W. Willcockson, Anaheim, Calif., assignor to United States Borax & Chemical Corporation, Los Angeles, Calif., a corporation of Nevada N Drawing. Filed Mar. 8, 1960, Ser. No. 13,418 4 Claims. (Cl. 21-605) This invention relates to the preservation of petroleum and petroleum fractions during storage and has more particular reference to the inhibiting of bacterial action on petroleum or petroleum fractions susceptible to such action in storage tanks.

In petroleum and petroleum fraction storage facilities, water is almost always present. The water is either deliberately added to the bottom of the tank to insure against loss of the petroleum by leakage or introduced into the tank by condensation of water vapor. Bacteria are almost always found in this water, and they are of a type which function at the interphase between the petroleum and the surface of the water, and due to their metabolism cause degradation of the petroleum. This metabolic degradation results in discoloration of the petroleum and the formation of an extremely undesirable, heavy, gummy sludge. This slude problem is especially pronounced in storage tanks in hot, humid areas.

Until the present invention, the most effective means for inhibiting bacterial growth in petroleum and petroleum fractions was the use of aqueous solutions of sodium or potassium tetraborates. The way in which the alkali metal borates were used was to dissolve them in water prior to introduction into the fuel storage tanks. This procedure is awkward and presents many handling and transportation problems; for example, to treat an 80,000 barrel storage tank requires dissolving about 8 tons of borax in 25,000 gallons of heated water. Since many fuel storage tanks are situated in remote places, this assemblage of heating equipment, storage tanks and water for preparing the borax solution is extremely inconvenient. If the solutions of the borates are prepared and then shipped to the tank site, there is considerable increase in expense due to the necessity of shipping such large quantities of water.

It is therefore an object of this invention to provide a method for effectively preventing sludge formation in petroleum and petroleum fractions due to bacterial activity.

A further object of this invention is to provide a method for adding a bactericide to petroleum and petroleum fractions which substantially completely eliminates the need for aqueous solutions.

Other objects will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the Ways in which the principle of the invention may be employed.

Broadly stated, the present invention comprises the method of preventing bacterial action in stored petroleum which comprises adding to said stored petroleum a liquid alkali metal organoborate selected from the group consisting of the condensation products of an alkali metal borate and a material selected from the group consisting of an ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, 2,3-butanediol, and 1,2-propanediol, said glycol borate condensation products consisting essentially of a mole ratio of from about 6:1 to about 20:1 of diol to equivalent alkali metal tetraborate, and said condensation products added to tank in bactericidal amounts.

In practicing the present invention, the glycol borate condensation product is added in an amount equivalent to that amount necessary to completely cover the bottom of the tank to be protected against bacterial action. If the tank is substantially water-free, an amount of condensation product is added which would substantially completely cover the bottom of the tank. If the tank already contains water, an amount of condensation product is used which is equivalent to that amount necessary to substantially completely cover the bottom of the tank if no water were present. By using the alkali metal borate condensation products of the present invention one readily overcomes the many defects present in the prior art methods. The present materials are all easily-handled liquids, which are non-corrosive and thus do not cause deterioration of the storage tanks. These materials are substantially insoluble in the petroleum and petroleum fractions and thus have no lowering effect on the heat of combustion of the petroleum and petroleum fractions. The present condensation products because of their greater density than the petroleum readily settle to the bottom of the tank. Further, of extreme interest and importance, it will also be noted that the present glycol borate condensation products readily combine with any water present to form a homogeneous solution and which solution retains its bactericidal effectiveness.

The following list is illustrative of the alkali metal borate condensation products useful in the present invention:

In the preferred embodiment of my invention I use sodium ethylene glycol borate having a mole ratio of glycol to equivalent sodium tetraborate of about 9:1. This glycol is available, inexpensive and easily handled.

The term petroleum, as used herein, is intended to include crude oil, kerosene, gasoline, lubricating oils, diesel fuels, and the like, as well as other hydrocarbons that are susceptible to bacterial degradation during storage.

The condensation products useful in the present inven tion are readily prepared using condensation processes well known to those skilled in the art. For example, the condensation product of sodium tetraborate and ethylene glycol is simply prepared by adding 1.0 mole of borax and 9.0 moles of the glycol to a reaction vessel and heating it to about to C. for sufiicient time to drive out water and give a product having a 9:1 mole ratio of glycol to equivalent sodium tetraborate. The condensation product is a clear liquid which can be added directly to the petroleum storage tank.

Thus, the present invention has provided an efficient means for inhibiting bacterial growth in storage tanks, and which means is independent of the amount of Water present in the storage tank. The present products are substantially inert with respect to the liquid contained in the storage tank and they are substantially completely compatible with any water which may be present in the tank.

Other modes of applying the principle of the invention may be employed, change being made as regards the the petroleum storage Sodium ethylene glycol borate Potassium ethylene glycol borate Sodium diethylene glycol borate Potassium diethylene glycol borate Sodium 1,2-propanediol borate Potassium 1,2-propanediol borate Sodium 2,3-butanediol borate Potassium 2,3-butanediol borate Sodium l,4-butanediol borate Potassium 1,4-butanediol borate Sodium triethylene glycol borate details described, provided the features stated in any of the following claims or the equivalent of such be employed.

1, therefore, particularly point out and distinctly claim as my invention:

1. In the storage of petroleum susceptible to microbial degradation, the improvement which comprises adding to the stored petroleum in bactericidal amounts a liquid alkali metal glycol borate having an alkylene group of 2 to 6 carbon atoms in length and containing a total of 2 to 20 carbon atoms.

2. In the storage of petroleum susceptible to microbial degradation, the improvement which comprises adding to the stored petroleum in bactericidal amounts a liquid alkali metal glycol borate selected from the class consisting of sodium ethylene glycol borate, potassium ethylene glycol borate, sodium dietbylene glycol borate, potassium diethylene glycol borate, sodium 1,2-propanediol borate, potassium 1,2-propanediol borate, sodium 2,3-butanediol borate, potassium 2,3-butanediol borate, sodium 1,4-butanedio1 borate, potassium 1,4-butanediol borate, and sodium triethylene glycol borate.

3. A composition comprising a major proportion of petroleum in contact With an aqueous phase and tending to undergo degradation and to deposit a sludge due to the presence in at least one of said petroleum and said aqueous phase of microorganisms that promote degradation of petroleum and a bactericidal amount of a liquid alkali metal glycol borate having an alkylene group of 2 to 6 carbon atoms in length and containing a total of 2 to 20 carbon atoms.

4. The composition of claim 3 where said alkali metal glycol borate comprises sodium ethylene glycol borate.

References Cited in the file of this patent UNITED STATES PATENTS 1,953,741 Bennett Apr. 3, 1934 2,882,227 Lindberg Apr. 14, 1959 2,883,412 Lowe Apr. 21, 1959 20 2,894,020 McManimie July 7, 1959 2,979,524 Wright et a1 Apr. 11, 1961 

1. IN THE STORAGE OF PETROLEUM SUSCEPTIBLE TO MICROBIAL DEGRADATION, THE IMPROVEMENT WHICHCOMPRISES ADDING TO THE STORED PETROLEUM IN BACTERICAL AMOUNTS A LIQUID ALKALI METAL GLYCOL BORATE HAVING AN ALKYLENE GROUP OF 2 TO 6 CARBON ATOMS IN LENGTH AND CONTAINING A TOTAL OF 2 TO 20 CARBON ATOMS. 